Subject: Test Your Knowledge (President Lincoln/HR2510).

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Rick
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Radio: President Lincoln & Uniden HR2510.
PCB Number: PB-111
Condition: Stock Radio only modification 11-meter conversion.
Symptoms: No TX power.
What is working: The Driver and Final are ok. The Display show TX with key-up. The CPU/MCU board is working ok. All voltage regulators are ok.
Skill Level: Medium

You are welcome to ask me any questions that are specific in nature just as if you were troubleshooting the radio.
The Schematic to solve this problem can be found here, http://www.cbtricks.com/radios/uniden/h ... sheet1.gif

Do not be shy and let us have some fun!

Rick Jackson (Euro Radio Co).
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by The Defpom »

ooh ooh I know !! :-)

Pick me, pick me ! :headbang:

Come on guys, this is good one, and a great idea by Rick, so join in, see if you can work out what is wrong.
Last edited by The Defpom on Sunday 16th Nov 2008, 21:00, edited 1 time in total.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by smokinjoe »

When you say driver and final are OK does this mean the volts are correct on both? Also are the pre driver volts correct?
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Using an oscilloscope, check for base to collector gain on the following transistor: Q124. Do you have a 27Mhz signal there with stronger signal at collector?

Check pin 5 of IC103 with an oscilloscope, do you have modulation when speaking into microphone?
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Well since I am still learning & understanding repairs I would normally not try to help anyone as I do not want to give anyone false information, however, since this is for fun I may do some posting as well. This was an excellent idea Rick, & hope to see more of this kind of thing in the future! Maybe what I learn here will help me with future troubleshooting.

Anything I post is stuff I would check / try.

Do you have about 13.8 volts DC on the Collector of both the Driver & Final?

What are the DC voltages at Q125 in TX mode?
Post the voltages for all three pins,

Q125:
E =
B =
C =
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by euhara »

I don't know anything but I think Q124 is the pre driver or is it Q134, and I would have you check the collector of that with the mike keyed for about 8 volts and go from there.

Just thought I would give this a try. Don't be too harsh with me.

Jim
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Re: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Smokinjoe,
There are volts at the Collectors of driver, and the final, and there are correct at 13.8vdc.
Pre-amp which one is that?
--------------------------------------------------------------------------------------------

Timrim,
There is no RF signal at Q124.
Check pin 5 of IC103 with an oscilloscope, do you have modulation when speaking into microphone?
The above quote has no bering on the fault.
The radio should still output RF on AM/FM with on modulation, and IC103 is the AF Amp and is not used to modulate the carrier in any mode.
-------------------------------------------------------------------------------------------------

Pioneer621,
Yes, there is 13.8 vdc on the Collector of the driver, and the final.

Q125: in TX
E = 7.95
B = 8.00
C = 0.25
-------------------------------------------------------------------------------------------------
Euhara
It is up to you to tell which transistor you want the info on.
-------------------------------------------------------------------------------------------------

Some of you maybe getting warmer
Last edited by Rick on Monday 17th Nov 2008, 5:14, edited 2 times in total.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by smokinjoe »

If the volts are correct at Q124 pre driver with no rf signal i would check volts at Q134 TX amp and for rf signal if volts are correct and still no rf signal i think IC106 is TX mixer i would check volts to see if they are correct and i think you should have a frequency reading at this point to check for not sure what it should be. Trying to learn more on trouble shooting myself hope I'm on the right track. Thanks Rick for all the help you have given me in the past this is a good idea to see if anyone is learning from all the support that is given on this site.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by zodiac »

You say the driver and final are OK and theres the correct voltage at both collectors.
Is there any current being drawn by them in TX ?.
How far is it.
Twice it's length from halfway.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Smokinjoe
I think you should re-read the answers as I think you have missed something.

Zodiac
There is on current being drawn.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by euhara »

Sorry I can't tell which is which without looking in the radio, but I suspect the pre driver has no volts because the transmitter is not being turned on. So I will just watch.

This is interesting though and a good idea Rick.

Regards, Jim
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

On IC-106, are voltages correct? Are you getting a 27Mhz signal on pin 9 output?

If so, check for 27 Mhz signal at Q134, if signal is missing and voltages are correct at Q134, it is likely that filter FT104 is bad.

If you do not have 27Mhz at pin9 of IC-106, Are both mixer signals present at IC 106? Put a frequency counter at TP-5, what is displayed? It should be 10.695 Mhz

Are the PLL output mixer frequencies there on IC -106 as you change through channels? Should be in the 36.695 - 40.095 Mhz range.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Timrim,
The signal is good at Pin 9 of the Mixer (IC106) and is 300mw 27.000 MHz, same as what is showing on the display.
The signal at the Base of Q134 is good at 190mw 27.000 MHz.
The frequency changes when you rotate the VFO knob.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Rick,

What is the DC voltage at Q125 in RX mode?
Post the voltages for the Base & Collector only, the emitter voltage appears fine at 7.95 volts, but the collector voltage is too low at 0.25 volts & the base voltage appears to be a little to high at 8 volts in TX mode.

Q125: RX Mode
B =
C =


So either something is possibly pulling the collector of Q125 towards ground, or something is not letting the base be pulled low enough to allow Q125 to conduct, or Q125 is faulty.

Check C130 to make sure it is not shorted.

Check Q125 to make sure it is within tolerance.


What are the DC voltages at Q136 in RX & TX mode?
Post the voltages for all three pins,

Q136: RX mode
E =
B =
C =


Q136: TX mode
E =
B =
C =
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Is there a 27Mhz signal at Q-134 emitter? If not than Q-134 is suspect. I would also check Resistors 164 and 167.
If a 27 MHZ signal does exist at the emitter of Q-134, then check for a 27 mhz signal at C120 L132 C134 junction, if 27mhz signal exists here than C120 is open or bad soldering. If 27mhz signal is not present there, then check soldering around L132 C134.

EDIT: Typo on above. I changed text to read:
Is there a 27Mhz signal at Q-134 emitter? If not than Q-134 is suspect.
Last edited by timrim on Monday 17th Nov 2008, 21:30, edited 1 time in total.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Pioneer621,
Q125: RX Mode
B = 8.00vdc
C = 0.25vdc

C130 is ok.

Q125 is ok.

Q136: RX mode
E = 0.00vdc
B = 0.05vdc
C = 8.00vdc

Q136: TX mode
E = 0.00vdc
B = 0.04vdc
C = 8.00vdc
-------------------------------------------------------------------------------------
Timrim,
There is a very weak signal at the Emitter of Q134.
R164 and R167 are ok.
C120, L132, C134 all appear to be ok.
All the solder joints around L132, C134 are good.

EDITED: after typo from Timrim,
Q134 tested ok.
Last edited by Rick on Tuesday 18th Nov 2008, 1:31, edited 1 time in total.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

I made a typo in my last post and just corrected it.

Is Q-134 bad? What are voltages on Emitter, Base and Collector?

If Q-134 is good, then I would look at bias, perhaps the transistor is not fully turning on. Check R-168 and R-169. Is C135 shorted?
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Rick,

What is the DC voltage on PIN-8 of IC104 in RX & TX mode?

IC104: RX mode
PIN-8 =


IC104: TX mode
PIN-8 =


Looks like Q136 is not getting switched on, as there is not enough voltage on the base. Check D147 & make sure it is not open circuit (faulty).


I probably won't be able to figure out the problem, but this is still a lot of fun!
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by captian_radio »

Well here's what I did years ago with a 2510 when using it with a 6 meter transverter. I removed the shorting bar near the final and driver to get the output down to the milliwatt level to feed my 6 meter transverter everything worked fine with the exception of the power output being in the low milliwatt range, not sure if its relevant or not but I have done this before when working on a 2510 (removing the shorting bar) to set the bias and forgot to replace it and wondered why I had no power output then realizing that I forgot to put the bar back in place :oops:
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Timrim,
Q135 is ok.
Check R168 and R169 and C135 all ok.
--------------------------------------------------------------------------------------------------
Pioneer621,
IC104: RX mode
PIN 8 = 1.4vdc

IC104: TX mode
PIN 8 = 1.6vdc

D147 is ok.
--------------------------------------------------------------------------------------------------
Captian_Radio,
It not that easy.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Rick,

What is the DC voltage on PIN-1, PIN-6, and PIN-7 and PIN-9 of IC104 in RX mode & TX mode?

IC104: RX mode
PIN-1 =
PIN-6 =
PIN-7 =
PIN-9 =


IC104: TX mode
PIN-1 =
PIN-6 =
PIN-7 =
PIN-9 =


It looks like the voltage on PIN-8 of IC104 is not going high enough in TX mode to conduct D147 & Q136.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Hmmm, I need to go back and re-read everything. I think I missed a valuable clue somewhere.
This is why it would be nice for manufacturers to put peak to peak voltages on various stages in service data.
Ok let me re-ask a question differently. Is the 27mhz signal at the base of Q-134 normal amplitude (if we know what normal is supposed to be)? If not, did you adjust L111 for maximum on scope at base of Q134? Is C-100 shorted?

Now unless I missed a clue somewhere, IC106 Mixer is good and output is normal. And if that is the case, the problem has to be from the filter to Q124 somewhere. It was established that the Voltage regulators (especially Q125) were good. That does not mean however that the voltage form the regulators is getting to the transistors, so I must ask: What is collector voltage of Q124 and Q134.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by ramblingman »

Q134 is either O/C,,Or someone has installed it the wrong way around.
Also Q124 May be O/C,,This could also lower the emitter of Q134.
Also check for broken traces around Q134..Also coupling cap. C-120
could be O/C..Also i would check D-165 and VR-113 for O/C,,This controls the biasing for the driver.Also L-132 Could have winding burnt into.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Pioneer621,
IC104: RX mode
PIN-1 = 2.85vdc
PIN-6 = 2.10vdc
PIN-7 = 2.10vdc
PIN-9 = 2.85vdc


IC104: TX mode
PIN-1 = 2.85vdc
PIN-6 = 1.95vdc
PIN-7 = 0.92vdc
PIN-9 = 2.85vdc
---------------------------------------------------------------------------------------------------

Timrim,
L111 has not been adjusted.
C-100 is not short.
The regulator (IC107) is getting to Q125.
The volts at the Collector of Q134 and Q124 are zero.
---------------------------------------------------------------------------------------------------

Ramblingman,
Q134 is not open circuit and is fitted in the correct way round.
Q124 is not open circuit.
There are no broken traces around Q134.
C120 is not open circuit.
D165 and VR113 are not open circuit.
L132 is ok.

-----------------------------------------
Some of you maybe getting hot.
Rick.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Rick,

The voltages on IC104 seem a bit low, especially the VCC Voltage on PIN-1 & PIN-9, which is probably why PIN-6 & PIN-7 have low voltage as well.

Check C75 as it may be shorted to very low ohms (faulty) & could be causing your transmit problem.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Is C-130 shorted? Did someone ask if Q124 was shorted emitter to collector?
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by euhara »

I guess I need for you to test D165 for open or short.

OOPS someone already asked that.

So check to see if the PA jack is stuck open just for fun.

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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Timrim,
C130 is ok, this question had already been asked.
Q124 is ok, this question had already been asked.
-------------------------------------------------------------------------------------

Euhara,
PA jack is ok.
------------------------------------------------------------------------------------

Pioneer621,
C75 is ok.

However, it is not worth keeping you hanging on any longer.

Ricks Quote
The fault was C60 which is in parallel with C75, it was reading 90 Ohms
on my Fluke 189 DVM.

End Quote.
------------------------------------------------------------------------------------

Kyle aka Pioneer621,
Congratulations Kyle.
Was on the right track from the start, I think he know more than he is letting on. :wink: :wink:

Dave aka Zodiac,
Was on the right track, by asking if (There is on current being drawn).
-----------------------------------------------------------------------------------------

Notes:
The radio came in with no TX output power. I did the following checks.
1. Check to see if the PA stage was drawing any current, and the answer was no.

2. Check to see if there was any volts’ getting to the Collectors of the Driver and Final, and answer was yes 13.8vdc.

3. Check the voltage regulator IC107 and there was 13.8vdc input and 8.00vdc output so the voltage regulator was ok.

4. Check the RX switching transistor Q127 and the voltage was so:
Q127: in RX
E = 7.25vdc.
B = 7.95vdc.
C = 8.00vdc.
Therefore, the RX switching transistor was ok.
Some may ask why I tested RX switching transistor, well if the transistor was short Collector Emitter then you would no be able get the TX switching transistor to turn on, as it is a PNP type.

5. Check the TX switching transistor Q125 and the voltage was so:
Q125: in TX
E = 7.95vdc.
B = 8.00vdc. (The Base needs to be negative with respect to the Emitter to turn on).
C = 0.25vdc.
Therefore, the TX switching transistor was not being turn on
I check the track that the Collector was feeding for a short to ground and none was found. I then un-soldered the Collector of Q136 and grounded the track and a Eureka we had TX power.

6. Re-soldered the Collector of Q136.
So I check the Op-Amp IC104 and found all the Pins voltages was wrong, which lead me to the supply Pin 1 which was found to be low at 2.85vdc which in turn lead me to C60 and C75, C60 had turn in to a resistor and was 90 Ohms, replace the cap and all ok. The total job was completed in less than 10 minutes
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Hello again Rick!

Glad to hear you found the problem! :D

I would have asked about C60 as well, but to me in the schematic I could not tell if it was in parallel with C75 or not, it almost looks like it connects to R88 only & ground, I figured I would start with C75 first since it is clearly connecting to PIN-1 of IC104 & Ground.

I definitely learned some from all of this. My current knowledge on repairs & troubleshooting is not to great yet, so I enjoy learning more when I can!

I own a few HR2510’s & really like the radios a lot, I have some very minor experience in repairs on them. I can’t remember what I was doing to one of mine & ended up blowing Q125, so I had to troubleshoot to that point but never as far as I did with the problem on your unit, so it was a good experience following the problem a little deeper into the circuit. I have never had any with C60 or C75 shorted, but I just looked back at one I repaired & I had to replace C75 as it leaked down to about 24uf (at least that is what I measure it around with my multi-meter, it reads some capacitance) & was causing distorted modulation in all modes, I actually have 2 Hr2510’s that had the very same problem.

Again Rick this was a great idea for posting! I think a lot of people would enjoy trying to troubleshoot a radio like we did here, I know I did. So I thank you Rick as this was a lot of fun & I think we all enjoyed trying to find the problem. Even if I am not participating I would enjoy watching posts like this.

We got to help you this time instead of you helping us, which was pretty cool! You help a lot of people repair there radios & give them great info, so I am glad we got to help you for a change even though you already new the problem. You posted everything very well too, you gave the radios, Name, Model, PCB#, Condition, Symptoms, What is working, & it made looking for the problem a lot easier, you even posted a schematic of the radio. If everyone posted most of that info right from the start it definitely helps.

Thanks again Rick! Take care everyone & we will talk to you all later! Kyle (Pioneer621)
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Rick »

Kyle aka Pioneer621,
I think you misunderstand me, I already know the answer to the fault, and it was just posted for a bit of fun.

I have found some good faults with the President Lincoln and the HR2510 over the years.

I have a quit a few more to post when I get my notes sorted out, some are real mind benders, but I will be fare and not post the ones which are to much as they may go on for to long and people will lose the plot.

Rick Jackson (Euro Radio Co).
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by The Defpom »

Well done on working out the problem!

Rick, maybe we should keep on the same radio for these puzzles, that way we can cover a lot of the common faults that occur to it, then people could use it as a reference for repairing the HR2510/Lincoln radios.

I have come across C60 being shorted myself before too, often the faults that occur are repeated time and time again, it certainly makes knowing what to check a lot easier !

I have a few good examples too for the HR, so if you run out of examples I may be able to jump in and provide some too.
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

Quote from my last post:[/quote]so I am glad we got to help you for a change even though you already new the problem[/quote].





Rick,

I understand exactly that this was for fun & you new the problem with the radio before you posted & this was to see if any of us could find the problem, I understood that before I started posting. Just as your Post Subject states: Test Your knowledge.

You were kind of testing us as you already new the answers, thats how I was looking at it anyway.

We got to test our knowledge & see if we could troubleshoot the problem.

With your knowledge I think you could repair anything, so I know what your post was for.


It will be interesting to see your future posts for us to try to diagnose the problems, & what problems they may have. You say some are real mind benders! I don’t know if I would even want to attempt them! You are right, posts for real difficult problems may go on to long.

Thanks again! Just wanted to clear that up. Take care. Kyle
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Hmmm, I missed a lot of posts :)
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by Pioneer621 »

The Defpom,

Yeah, I think we all had fun working out the problem!

That is an interesting idea about keeping on the same radio for the puzzles. Would give people great information on actually finding problems in a particular model radio & how to go about troubleshooting them. People can follow along with voltage checks, frequency checks, shorted or leaky capacitors, etc. I like the idea.

These HR radios are pretty popular & a source of info like that for them on one forum would be excellent!

----------------------------------------------------------------------------

Timrim,

I try to follow all the posts to keep up to date where we are at, I tended to want to skim through them at first, but thought it would be best to read them thoroughly to see what all was working & what was not.


Take care & we will talk to you all later! Kyle (Pioneer621)
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by timrim »

Yea, somewhere along the line, I went off course and I was stuck on 2 transistors that did not have their collector voltage! :oops:
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Subject: Test Your Knowledge (President Lincoln/HR2510).

Post by absorbentgnome »

Brilliant thread, well done Pioneer621 for finding the problem!
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